There is provided a method for making lateral openings out of a wellbore. More precisely there is provided a method for making lateral openings out of a wellbore into a well formation, where fluid is made to flow through a motherbore tubular like a completion or production pipe and then through at least one needle pipe that is aimed at the formation. There is also provided a device for practicing the method.
The motherbore tubular forms a major conduit through at least a part of the wellbore, while the needle pipe is of a much smaller diameter and intended to be able to extend from the mother tubular and into the formation.
It is well known to treat a carbonate well formation with acid in order to stimulate the well.
According to prior art, relatively large quantities of hydrochloric acid have to be pumped into the well. Often the treatment has limited success. If the acid is not flowing into the intended sections of the well, the treatment may even lead to undesired increase in gas and water production.
The lack of desirable effects could be due to a breakdown of the formation matrix or that the acid follows natural fractures in the formation.
Several methods have been proposed for the purpose of improving the acid treatment. It is thus known to position a deflecting shoe at a lateral opening in the motherbore tubular. A jetting hose is then fed from the surface and deflected through the opening in the motherbore tubular and further on into the formation as the acid dissolves the formation. Although safeguarding that the acid is flowing into the desired part of the formation, the method is producing unnecessary large passages in the formation and the lateral openings are jetted sequentially.
Norwegian patent NO 323927 proposes to direct a narrow pipe towards the formation. Several narrow pipes may be positioned on the motherbore tubular, and a flowing acid or another fluid may thus produce a number of tiny openings in the formation. A disadvantage of this process is limited reach of the narrow pipes into the formation.